Analysing Road Traffic Situation in Lilongwe: An Agent Based Modelling (ABM) Approach

A 15, 451 km road network forms the main mode of transport for Malawi with 26 % paved. With increasing number of vehicles and elongated travel times during rush hour the study analysed the traffic situation on the M1 road between Mchinji and Area 18 roundabouts in Lilongwe City using an agent-based model (ABM). The methodology used game theory’s traffic grip model to analyse traffic flow by controlling traffic variables such as lights, speed limits and the number of vehicles. Each intersection was treated as non-cooperative game where each agent tried to minimize its queue resulting into Q−Nash’s equilibrium as the solution. The ABM tested the empirical relationships of traffic flow parameters in terms of density, flow, acceleration, deceleration, speed, time lost in traffic congestion and fuel consumption. The model was calibrated using traffic data collected through observing 1,312 vehicles sampled against 24,977. The observation results from the road junctions reveal that on average, a vehicle takes 20 mins 18 seconds, 37 minutes 6 seconds, 44 minutes 21 seconds and 58 minutes 53 seconds to exit Chitukuko, Bwandilo, Chilambula roads and Area 18 roundabout respectively upon entering the M1 at Mchinji roundabout. This data was then used to calibrate the business-as-usual model for the peak hour scenario for the road junctions. The model results show that a selected vehicle entering Chitukuko junction travels at an average speed of 22.60 km/hr, until it exits that junction. On average the selected motorists spend 2.52 l/km with a traffic density of 72 v/km. If dualized average speeds improved to 41.54 km/hr while the traffic density declined to 54.42 v/km, saving motorists MK 3,921,624.00 annually. The predictive model of the dual carriage informed that by 2021, commuters will spend MK 5,187,168 on fuel more than single-lane business as usual scenario of 2019.

Vehicle delay at the crossroads and road junctions

The main types of maneuvers on crossings and adjoints of highways in one level are studied. The probability of an unobstructed injection of a vehicle from a secondary to the main road and vice versa, taking into account the average length of the free interval between the vehicles of the main stream, is determined. The dependence of the duration of free intervals, and their number, on the intensity of traffic, the composition of the traffic flow, and the speed of vehicles, was found. A series of equations was obtained for determining the total transport delay in the performance of various types of maneuvers, depending on the type of intersection or adjacency. Vehicle delays at crossings and adjacent roads are used to economically justify changing their parameters. Therefore, the work is designed to minimize the delays of vehicles at crossings and interconnections both in one and at different levels.

The use of simulation when designing road junctions

The high level of motorization in most countries of the world is the reason for the increase in the number of car accidents. Currently, it is understood that a further increase in the number of cars without significant changes in the transport infrastructure will only aggravate the already difficult situation on roads. The article addresses the issues of road traffic injuries and statistical information on road accidents. The analysis of the work of leading transport engineers presents the results of studies on the use of computer modeling tools for designing road conditions at various levels. From the presented analysis, it is possible to conclude that the most suitable tool for assessing the safety of road junctions is the PTV VISSIM software package, which also allows to export vehicle trajectories to SSAM software. In the framework of the analytic survey of the intersection safety, based on the analysis of vehicle trajectories, the parameters of the future conflict of the planned road junctions were established. Studies have shown that a road junction at different levels makes possible to triple the safety of junctions in comparison with the roundabout. The use of simulation allows not to wait for emergency cases, but to evaluate hypothetical structures and alternative layout options for road junctions, where it is not possible to use traditional, statistical models for assessing the probability of car accidents.

Analysis of the road safety assessment in the areas of road nodes - questionnaire surveys

Road junctions constitute one of the most important elements of road infrastructure. These are the special types of intersections, the construction of which results in an increase in the level of road safety in the areas of expressways and motorways. A wrongly designed or insufficiently marked and illuminated road junction may mislead participants and cause dangerous situations. The article presents author's surveys conducted among drivers on the subject of road safety assessment in the areas of road junctions.